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Intelligent measurement of electrical and magnetic quantities
Jablonski
have been calculated according to the recent achievements in metrology. Table 1 gives the list of variables, differential coefficients and their values, nominal values of variables and their errors. The upper limit of radius is R -- 32 ram. Theoretically radius R could be much bigger, consequently increasing N. The experiments showed technical problems by making the mirror arms longer than 120 mm (required flatness A/40, right-angle accuracy 1"). Further, it causes increase of weight, which results in greater friction and wear. The counters used have a frequency response of 1×10 -9 Hz. Theoretically, they permit a rotational speed up to 10 revolutions per second, but tilts which occur during rotation cause instantaneous accelerations and result in frequency changes of the order of 1 0 4 . That is why the speed of rotation was limited to 2 rev/min. An interpolation of more than 103 is not suggested mainly because of the limited accuracy of roundness of measuring instruments (systematic roundness errors are written into a computer memory as corrections) which is about 0.01/xm. The "0-position" (~0) which corresponds to No count is computed from the formula N. = 1/2(Nm,x+Nmi,). The system does not require any reference standard. The calibration is a self-checking process and it needs just one rotation to determine an actual value of R. To define cosine error it is necessary to set up an interferometer in order to observe the interference fringes. It can be done within the accuracy of 1" The calculated accuracy limit, based on the partial errors given in Table 1, is shown in Fig 4. This low-dependence is because the errors e R and e0the most significant - are determined in the self-calib-
ration process which precedes the measurement. The resolution within the most sensitive areas is 0.0025" and the accuracy of about 0.006". References
Downs, M. J. 1989, "Achievement of the optimum performance from laser interferometer systems when applied to precision length measurement in the free atmosphere", Proc 2nd IMEKO TC14 Int Symp ISMQC/IMEKO 89, Beijing, China, 19-36. Kunzmann, H. 1989, "Today's limits of accuracy in dimensional metrology", Proc 2nd IMEKO TC14 Int Symp ISMQC/IMEKO 89, Beijing, China, 5-18. Tarbeyev, Y. V. 1984, "Theoretical and practical limits of measurement accuracy", Measurement, 2(1), 18-22. Debler, E. 1977, "Winkelinterferometer mit einem Messbereich yon 95°'', Feinwerktechnik und Messtechnik, 85(4), 166-171. Mintrop, It. and Debler, E. 1977, "Interferometrische Winkelmessungen in grossen Messbereichen", Feinwerktechnik und Messtechnik, 85(2), 82-85. Gliwinski, J. 1979, "Laser interferometer for angle measurement", Acta IMEKO 1979. Publishing house of the Hungarian Academy of Science, Budapest, Hungary, 477-482. Jab~onski, R. 1986, "Interferometric measurement of angles", Measurement, 4(4), 148-153. Jabl'onski, R. 1985, "Laser interferometer system for measurement and calibration of angles in the range of 27r rad", Proc X Congress IMEKO, Prague, Czechoslovakia, 12, 1-8.
Intelligent Measurement of Electrical and Magnetic Quantities The 4th international symposium on "Intelligent measurement of electrical and magnetic quantities", organised by IMEKO Technical Committee TC-4, will be held at Varna, Bulgaria, on 15-17 November 1990. The general scope of the symposium is to report and review the state of the art of electrical and magnetic measurements. Special emphasis is put on the advancement in computerised measurements and intelligent instrumentation. Topics to be included are: 1. Measurement theory, metrological problems and information processing. 2. Intelligent electrical and magnetic devices and systems. Measurement Vol 8 No 3, JuI-Sep 1990
3. Data acquisition systems. 4. Implementation of personal computers in measurements. 5. Technical diagnostics in electronics and computerised instrumentation. 6. Expert systems in measurement. 7. Computerised education in electrical engineering. The symposium will take place at the Joliot Curie International House of Scientists, Drouzba, Varna, Bulgaria. Full details are available from: Dr Iv. Adarski, Institute for Microprocessor Instruments and Systems, Lenin bul. 7-th kin, 1184 Sofia, Bulgaria (Tfx: 777 104 Tlx: 22711 Tlf: 72-36-62). 131
have been calculated according to the recent achievements in metrology. Table 1 gives the list of variables, differential coefficients and their values, nominal values of variables and their errors. The upper limit of radius is R -- 32 ram. Theoretically radius R could be much bigger, consequently increasing N. The experiments showed technical problems by making the mirror arms longer than 120 mm (required flatness A/40, right-angle accuracy 1"). Further, it causes increase of weight, which results in greater friction and wear. The counters used have a frequency response of 1×10 -9 Hz. Theoretically, they permit a rotational speed up to 10 revolutions per second, but tilts which occur during rotation cause instantaneous accelerations and result in frequency changes of the order of 1 0 4 . That is why the speed of rotation was limited to 2 rev/min. An interpolation of more than 103 is not suggested mainly because of the limited accuracy of roundness of measuring instruments (systematic roundness errors are written into a computer memory as corrections) which is about 0.01/xm. The "0-position" (~0) which corresponds to No count is computed from the formula N. = 1/2(Nm,x+Nmi,). The system does not require any reference standard. The calibration is a self-checking process and it needs just one rotation to determine an actual value of R. To define cosine error it is necessary to set up an interferometer in order to observe the interference fringes. It can be done within the accuracy of 1" The calculated accuracy limit, based on the partial errors given in Table 1, is shown in Fig 4. This low-dependence is because the errors e R and e0the most significant - are determined in the self-calib-
ration process which precedes the measurement. The resolution within the most sensitive areas is 0.0025" and the accuracy of about 0.006". References
Downs, M. J. 1989, "Achievement of the optimum performance from laser interferometer systems when applied to precision length measurement in the free atmosphere", Proc 2nd IMEKO TC14 Int Symp ISMQC/IMEKO 89, Beijing, China, 19-36. Kunzmann, H. 1989, "Today's limits of accuracy in dimensional metrology", Proc 2nd IMEKO TC14 Int Symp ISMQC/IMEKO 89, Beijing, China, 5-18. Tarbeyev, Y. V. 1984, "Theoretical and practical limits of measurement accuracy", Measurement, 2(1), 18-22. Debler, E. 1977, "Winkelinterferometer mit einem Messbereich yon 95°'', Feinwerktechnik und Messtechnik, 85(4), 166-171. Mintrop, It. and Debler, E. 1977, "Interferometrische Winkelmessungen in grossen Messbereichen", Feinwerktechnik und Messtechnik, 85(2), 82-85. Gliwinski, J. 1979, "Laser interferometer for angle measurement", Acta IMEKO 1979. Publishing house of the Hungarian Academy of Science, Budapest, Hungary, 477-482. Jab~onski, R. 1986, "Interferometric measurement of angles", Measurement, 4(4), 148-153. Jabl'onski, R. 1985, "Laser interferometer system for measurement and calibration of angles in the range of 27r rad", Proc X Congress IMEKO, Prague, Czechoslovakia, 12, 1-8.
Intelligent Measurement of Electrical and Magnetic Quantities The 4th international symposium on "Intelligent measurement of electrical and magnetic quantities", organised by IMEKO Technical Committee TC-4, will be held at Varna, Bulgaria, on 15-17 November 1990. The general scope of the symposium is to report and review the state of the art of electrical and magnetic measurements. Special emphasis is put on the advancement in computerised measurements and intelligent instrumentation. Topics to be included are: 1. Measurement theory, metrological problems and information processing. 2. Intelligent electrical and magnetic devices and systems. Measurement Vol 8 No 3, JuI-Sep 1990
3. Data acquisition systems. 4. Implementation of personal computers in measurements. 5. Technical diagnostics in electronics and computerised instrumentation. 6. Expert systems in measurement. 7. Computerised education in electrical engineering. The symposium will take place at the Joliot Curie International House of Scientists, Drouzba, Varna, Bulgaria. Full details are available from: Dr Iv. Adarski, Institute for Microprocessor Instruments and Systems, Lenin bul. 7-th kin, 1184 Sofia, Bulgaria (Tfx: 777 104 Tlx: 22711 Tlf: 72-36-62). 131